---
id: CVE-2026-91939
title: >-
  Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize()
  without allowed_classes restriction, allowing unauthenticated attackers to
  instantiate arbitrary PHP classes with attacker-controlled properties
summary: >-
  Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize()
  without allowed_classes restriction, allowing unauthenticated attackers to
  instantiate arbitrary PHP classes with attacker-controlled properties.
  Attackers can ex…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-502
vendor: Cotonti
product: Cotonti
affected:
  - Cotonti >= 1.0.0 <= 1.0.0
published: '2026-09-15'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T20:21:01.047'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91939'
references:
  - url: 'https://github.com/Cotonti/Cotonti'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/comments.setup.php
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/controllers/actions/DisplayAction.php
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/inc/CommentsWidget.php
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Cotonti/Cotonti/issues/1888'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Cotonti/Cotonti/pull/1889'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/cotonti-1.0.0-comments-plugin-php-object-injection-via-ci-parameter
    label: disclosure@vulncheck.com
  - url: 'https://github.com/Cotonti/Cotonti/issues/1888'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-16T19:17:38.681650Z'
ingestedAt: '2026-09-15T21:44:50.654Z'
epss: 0.00594
epssPercentile: 0.46799
---

## Overview

Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads to trigger gadget chains and achieve database manipulation or code execution.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.